Multi-speed transmission

ABSTRACT

A transmission is provided having an input member, an output member, an intermediate member, four planetary gear sets, a plurality of interconnecting members, and five torque transmitting mechanisms. The planetary gear sets include first, second and third members. The plurality of interconnecting members each continuously interconnect one of the first, second and third members of the planetary gear sets with another one of the first, second and third members of the planetary gear sets, and a stationary member. The torque transmitting mechanisms are selectively engageable in combinations of at least two to establish at least eight forward speed ratios and at least one reverse speed ratio between the input member and the output member.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is continuation of U.S. application Ser. No. 12/057,071filed on Mar. 27, 2008 and as such, under 35 U.S.C. §120, claimspriority benefit of the filing date of the above referenced application.The disclosure of the above application is incorporated herein byreference.

FIELD

The invention relates generally to a multiple speed transmission havinga plurality of planetary gear sets and a plurality of torquetransmitting devices and more particularly to a transmission havingeight or more speeds, four planetary gear sets and a plurality of torquetransmitting devices.

BACKGROUND

The statements in this section merely provide background informationrelated to the present disclosure and may or may not constitute priorart.

A typical multiple speed transmission uses a combination of frictionclutches, planetary gear arrangements and fixed interconnections toachieve a plurality of gear ratios. The number and physical arrangementof the planetary gear sets, generally, are dictated by packaging, costand desired speed ratios.

While current transmissions achieve their intended purpose, the need fornew and improved transmission configurations which exhibit improvedperformance, especially from the standpoints of efficiency,responsiveness and smoothness and improved packaging, primarily reducedsize and weight, is essentially constant. Accordingly, there is a needfor an improved, cost-effective, compact multiple speed transmission.

SUMMARY

A transmission is provided having an input member, an output member, anintermediate member, four planetary gear sets, a plurality of couplingmembers and a plurality of torque transmitting devices. Each of theplanetary gear sets includes first, second and third members. The torquetransmitting devices are for example clutches and brakes.

An embodiment of the transmission includes an input member, an outputmember, an intermediate member, and first, second, third and fourthplanetary gear sets each having first, second and third members. A firstinterconnecting member continuously interconnects the first member ofthe first planetary gear set with a stationary member, a secondinterconnecting member continuously interconnects the second member ofthe first planetary gear set with the third member of the secondplanetary gear set, a third interconnecting member continuouslyinterconnects the third member of the first planetary gear set with thefirst member of the fourth planetary gear set, a fourth interconnectingmember continuously interconnects the first member of the secondplanetary gear set with the first member of the third planetary gearset, and a fifth interconnecting member continuously interconnects thesecond member of the third planetary gear set and the output member withthe second member of the fourth planetary gear set. Five torquetransmitting devices are selectively engageable to interconnect one ofthe first, second, and third members with at least one of another of thefirst, second, third members, the intermediate member, and thestationary member. The torque transmitting devices are selectivelyengageable in combinations of at least three to establish at least eightforward speed ratios and at least one reverse speed ratio between theinput member and the output member.

In one aspect of the present invention, a first of the five torquetransmitting devices is selectively engageable to interconnect at leastone of the input member and the second member of the second planetarygear set with the intermediate member.

In another aspect of the present invention, a second of the five torquetransmitting devices is selectively engageable to interconnect at leastone of the third member of the first planetary gear set and the firstmember of the fourth planetary gear set with the intermediate member.

In yet another aspect of the present invention, a third of the fivetorque transmitting devices is selectively engageable to interconnect atleast one of the first member of the second planetary gear set and thefirst member of the third planetary gear set with the intermediatemember.

In yet another aspect of the present invention, a fourth of the fivetorque transmitting devices is selectively engageable to interconnectthe third member of the fourth planetary gear set with the intermediatemember.

In yet another aspect of the present invention, a fifth of the fivetorque transmitting devices is selectively engageable to interconnectthe third member of the third planetary gear set with the stationarymember.

In yet another aspect of the present invention, the first members aresun gears, the second members are carrier members, and the third membersare ring gears.

In yet another aspect of the present invention, the input member iscontinuously interconnected with the second member of the secondplanetary gear set and wherein the output member is continuouslyinterconnected with at least one of the second member of the thirdplanetary gear set and the second member of the fourth planetary gearset.

In yet another aspect of the present invention, one of the torquetransmitting devices is a brake and four of the torque transmittingdevices are clutches.

In yet another aspect of the present invention, the stationary member isa transmission housing.

Further objects, aspects and advantages of the present invention willbecome apparent by reference to the following description and appendeddrawings wherein like reference numbers refer to the same component,element or feature.

DRAWINGS

The drawings described herein are for illustration purposes only and arenot intended to limit the scope of the present disclosure in any way;

FIG. 1 is a lever diagram of an embodiment of an eight speedtransmission according to the present invention;

FIG. 2 is a diagrammatic view of an embodiment of an eight speedtransmission according to the present invention; and

FIG. 3 is a truth table presenting the state of engagement of thevarious torque transmitting devices in each of the available forward andreverse speeds or gear ratios of the transmission illustrated in FIGS. 1and 2.

DETAILED DESCRIPTION

The following description is merely exemplary in nature and is notintended to limit the present disclosure, application, or uses.

At the outset, it should be appreciated that the embodiments of thetransmission of the present invention have an arrangement of permanentmechanical connections between the elements of the four planetary gearsets in common. These mechanical connections generically link or relatethe transmission embodiments. More specifically, a first component orelement of a first planetary gear set is permanently coupled to a groundor a transmission housing. A second component or element of the firstplanetary gear set is permanently coupled to a first component orelement of a second planetary gear set. A third component or element ofthe second planetary gear set is permanently coupled to a thirdcomponent or element of a third planetary gear set. A second componentor element of the third planetary gear set is permanently coupled to asecond component or element of a fourth planetary gear set. A thirdcomponent or element of the first planetary gear set is permanentlycoupled to a first component or element of the fourth planetary gearset.

Referring now to FIG. 1, an embodiment of an eight speed transmission 10is illustrated in a lever diagram format. A lever diagram is a schematicrepresentation of the components of a mechanical device such as anautomatic transmission. Each individual lever represents a planetarygear set wherein the three basic mechanical components of the planetarygear are each represented by a node. Therefore, a single lever containsthree nodes: one for the sun gear, one for the planet gear carrier, andone for the ring gear. The relative length between the nodes of eachlever can be used to represent the ring-to-sun ratio of each respectivegear set. These lever ratios, in turn, are used to vary the gear ratiosof the transmission in order to achieve an appropriate ratios and ratioprogression. Mechanical couplings or interconnections between the nodesof the various planetary gear sets are illustrated by thin, horizontallines and torque transmitting devices such as clutches and brakes arepresented as interleaved fingers. If the device is a brake, one set ofthe fingers is grounded. Further explanation of the format, purpose anduse of lever diagrams can be found in SAE Paper 810102, “The LeverAnalogy: A New Tool in Transmission Analysis” by Benford and Leisingwhich is hereby fully incorporated by reference.

The transmission 10 includes an input shaft or member 12, a firstplanetary gear set 14 having three nodes: a first node 14A, a secondnode 14B and a third node 14C, a second planetary gear set 16 havingthree nodes: a first node 16A, a second node 16B and a third node 16C, athird planetary gear set 18 having three nodes: a first node 18A, asecond node 18B and a third node 18C, a fourth planetary gear set 20having three nodes: a first node 20A, a second node 20B and a third node20C and an output shaft or member 22.

The first node 14A of the first planetary gear set 14 is coupled toground, stationary member, or a transmission housing 50. The second node14B of the first planetary gear set 14 is coupled to the first node 16Aof the second planetary gear set 16. The third node 14C of the firstplanetary gear set 14 is coupled to the first node 20A of the fourthplanetary gear set 20. The second node 16B of the second planetary gearset 16 is coupled to the input shaft or member 12. The third node 16C ofthe second planetary gear set 16 is coupled to the third node 18C of thethird planetary gear set 18. The second node 18B of the third planetarygear set 18 is coupled to the second node 20B of the fourth planetarygear set 20. The output shaft or member 22 is coupled to the second node18B of the third planetary gear set 18.

A first clutch 26 selectively connects the second node 16B of the secondplanetary gear set 16 and input shaft or member 12 to an intermediatenode, element, or member 60. A second clutch 28 selectively connects theintermediate node 60 to the third node 14C of the first planetary gearset 14. A third clutch 30 selectively connects the intermediate node 60to the third node 16C of the second planetary gear set 16 and the thirdnode 18C of the third planetary gear set 18. A fourth clutch 32selectively connects the intermediate node 60 to the third node 20C ofthe fourth planetary gear set 20. A brake 34 selectively connects thefirst node 18A of the third planetary gear set 18 to the ground,stationary member, or transmission housing 50.

Referring now to FIG. 2, a stick diagram presents a schematic layout ofthe embodiment of the eight speed transmission 10 according to thepresent invention. In FIG. 2, the numbering from the lever diagram ofFIG. 1 is carried over. The clutches, brake and couplings arecorrespondingly presented whereas the nodes of the planetary gear setsnow appear as components of planetary gear sets such as sun gears, ringgears, planet gears and planet gear carriers.

For example, planetary gear set 14 includes sun gear member 14A, planetgear carrier member 14B and ring gear member 14C. Sun gear member 14A isconnected to ground, stationary member or transmission housing 50through a first interconnecting shaft or member 42. The planet gearcarrier member 14B rotatably supports a set of planet gears 14D (onlyone shown) and is connected for common rotation with a secondinterconnecting shaft or member 44. Ring gear member 14C is connectedfor common rotation with a third interconnecting shaft or member 46 anda fourth interconnecting shaft or member 48. Planet gears 14D are eachconfigured to intermesh with both sun gear member 14A and ring gearmember 14C.

The input shaft or member 12 is preferably continuously connected to anengine (not shown) or to a turbine of a torque converter (not shown).The output shaft or member 22 is preferably continuously connected withthe final drive unit or transfer case (not shown).

Planetary gear set 16 includes sun gear member 16C, planet carriermember 16B that rotatably supports a set of planet gears 16D and ringgear member 16A. Sun gear member 16C is connected for common rotationwith a fifth interconnecting shaft or member 52. Planet carrier member16B is connected for common rotation with input shaft or member 12 and asixth interconnecting shaft or member 54. Ring gear member 16A isconnected for common rotation with second interconnecting shaft ormember 44. Planet gears 16D are each configured to intermesh with bothsun gear member 16C and ring gear member 16A.

Planetary gear set 18 includes sun gear member 18C, ring gear member 18Aand planet carrier member 18B that rotatably supports a set of planetgears 18D. Sun gear member 18C is connected for common rotation with thefifth interconnecting shaft or member 52. Ring gear member 18A isconnected to a brake 34 as will be described in further detail below.Planet carrier member 18B is connected for common rotation with aseventh interconnecting shaft or member 56 and output shaft or member22. Planet gears 18D are each configured to intermesh with both sun gearmember 18C and ring gear member 18A.

Planetary gear set 20 includes sun gear member 20A, ring gear member 20Cand planet carrier member 20B that rotatably supports a set of planetgears 20D. Sun gear member 20A is connected for common rotation with thethird interconnecting shaft or member 46. Ring gear member 20C isconnected for common rotation with an eighth interconnecting shaft ormember 58. Planet carrier member 20B is connected for common rotationwith the seventh interconnecting shaft or member 56. Planet gears 20Dare each configured to intermesh with both sun gear member 20A and ringgear member 20C.

The torque-transmitting devices or clutches 26, 28, 30, 32 and brake 34allow for selective interconnection of the shafts or interconnectingmembers, members of the planetary gear sets and the housing. Forexample, first clutch 26 is selectively engageable to connect anintermediate shaft or member 60 to the sixth interconnecting shaft ormember 54. Second clutch 28 is selectively engageable to connect theintermediate shaft or member 60 to the fourth interconnecting shaft ormember 48. Third clutch 30 is selectively engageable to connect theintermediate shaft or member 60 to the fifth interconnecting shaft ormember 52. Fourth clutch 32 is selectively engageable to connect theintermediate shaft or member 60 to the eighth interconnecting shaft ormember 58. Brake 34 is selectively engageable to connect the ring gearmember 18A to ground, stationary member, or transmission housing 50 torestrict rotation of the ring gear member 18A relative to transmissionhousing 50.

Referring now to FIGS. 2 and 3, the operation of the embodiment of theeight speed transmission 10 will be described. It will be appreciatedthat the transmission 10 is capable of transmitting torque from theinput shaft or member 12 to the output shaft or member 22 in at leasteight forward speeds or torque ratios and at least one reverse speed ortorque ratio. Each forward and reverse speed or torque ratio is attainedby engagement of one or more of the torque-transmitting devices (i.e.first clutch 26, second clutch 28, third clutch 30, fourth clutch 32 andbrake 34), as will be explained below. FIG. 3 is a truth tablepresenting the various combinations of torque-transmitting devices thatare activated or engaged to achieve the various gear states. Actualnumerical gear ratios of the various gear states are also presentedalthough it should be appreciated that these numerical values areexemplary only and that they may be adjusted over significant ranges toaccommodate various applications and operational criteria of thetransmission 10. An example of the gear ratios that may be obtainedusing the embodiments of the present invention are also shown in FIG. 3.Of course, other gear ratios are achievable depending on the geardiameter, gear teeth count and gear configuration selected.

To establish reverse gear, third clutch 30, fourth clutch 32, and brake34 are engaged or activated. Third clutch 30 connects the intermediateshaft or member 60 to the fifth interconnecting shaft or member 52.Fourth clutch 32 connects the intermediate shaft or member 60 to theeighth interconnecting shaft or member 58. Brake 34 connects ring gearmember 18A to transmission housing 50 to restrict rotation of ring gearmember 18A relative to transmission housing 50. Likewise, the eightforward ratios are achieved through different combinations of clutch andbrake engagement, as shown in FIG. 3.

It will be appreciated that the foregoing explanation of operation andgear states of the eight speed transmission 10 assumes, first of all,that all clutches and brake not specifically referenced in a given gearstate are inactive or disengaged and, second of all, that during gearshifts, i.e., changes of gear state, between at least adjacent gearstates, a clutch or brake engaged or activated in both gear states willremain engaged or activated.

The description of the invention is merely exemplary in nature andvariations that do not depart from the gist of the invention areintended to be within the scope of the invention. Such variations arenot to be regarded as a departure from the spirit and scope of theinvention.

1. A transmission comprising: an input member; an output member; anintermediate member; first, second, third and fourth planetary gear setseach having first, second and third members; a plurality ofinterconnecting members each continuously interconnecting one of thefirst, second, and third members of the planetary gear sets with anotherone of the first, second, and third members of the planetary gear sets,and a stationary member; a first torque transmitting device selectivelyengageable to interconnect the second member of the second planetarygear set and the input member with the intermediate member; a secondtorque transmitting device selectively engageable to interconnect thethird member of the first planetary gear set and the first member of thefourth planetary gear set with the intermediate member; a third torquetransmitting device selectively engageable to interconnect the firstmember of the second planetary gear set and the first member of thethird planetary gear set with the intermediate member; a fourth torquetransmitting device selectively engageable to interconnect the thirdmember of the fourth planetary gear set with the intermediate member;and a fifth torque transmitting device selectively engageable tointerconnect the third member of the third planetary gear set with astationary member, and wherein the torque transmitting devices areselectively engageable in combinations of at least three to establish aplurality of forward speed ratios and at least one reverse speed ratiobetween the input member and the output member.
 2. The transmission ofclaim 1 wherein a first of the five interconnecting members continuouslyinterconnect the first member of the first planetary gear set with thestationary member.
 3. The transmission of claim 2 wherein a second ofthe five interconnecting members continuously interconnect the secondmember of the first planetary gear set with the third member of thesecond planetary gear set.
 4. The transmission of claim 3 wherein athird of the five interconnecting members continuously interconnect thethird member of the first planetary gear set with the first member ofthe fourth planetary gear set.
 5. The transmission of claim 4 wherein afourth of the five interconnecting members continuously interconnect thefirst member of the second planetary gear set with the first member ofthe third planetary gear set.
 6. The transmission of claim 5 wherein afifth of the five interconnecting members continuously interconnect thesecond member of the third planetary gear set with the second member ofthe fourth planetary gear set.
 7. The transmission of claim 1 whereinthe first members are sun gears, the second members are carrier members,and the third members are ring gears.
 8. The transmission of claim 1wherein the input member is continuously interconnected with the secondmember of the second planetary gear set and wherein the output member iscontinuously interconnected with the second member of the thirdplanetary gear set and the second member of the fourth planetary gearset.
 9. The transmission of claim 1 wherein one of the torquetransmitting devices is a brake and four of the torque transmittingdevices are clutches.
 10. The transmission of claim 1 wherein thestationary member is a transmission housing.
 11. A transmissioncomprising: an input member; an output member; an intermediate member;first, second, third and fourth planetary gear sets each having first,second and third members, wherein the input member is continuouslyinterconnected with the second member of the second planetary gear setand wherein the output member is continuously interconnected with thesecond member of the third planetary gear set and the second member ofthe fourth planetary gear set; a plurality of interconnecting memberseach continuously interconnecting one of the first, second, and thirdmembers of the planetary gear sets with another one of the first,second, and third members of the planetary gear sets, and a stationarymember; a first torque transmitting device selectively engageable tointerconnect the second member of the second planetary gear set and theinput member with the intermediate member; a second torque transmittingdevice selectively engageable to interconnect the third member of thefirst planetary gear set and the first member of the fourth planetarygear set with the intermediate member; a third torque transmittingdevice selectively engageable to interconnect the first member of thesecond planetary gear set and the first member of the third planetarygear set with the intermediate member; a fourth torque transmittingdevice selectively engageable to interconnect the third member of thefourth planetary gear set with the intermediate member; and a fifthtorque transmitting device selectively engageable to interconnect thethird member of the third planetary gear set with a stationary member,and wherein the torque transmitting devices are selectively engageablein combinations of at least three to establish a plurality of forwardspeed ratios and at least one reverse speed ratio between the inputmember and the output member.
 12. The transmission of claim 11 wherein afirst of the five interconnecting members continuously interconnect thefirst member of the first planetary gear set with the stationary member.13. The transmission of claim 12 wherein a second of the fiveinterconnecting members continuously interconnect the second member ofthe first planetary gear set with the third member of the secondplanetary gear set.
 14. The transmission of claim 13 wherein a third ofthe five interconnecting members continuously interconnect the thirdmember of the first planetary gear set with the first member of thefourth planetary gear set.
 15. The transmission of claim 14 wherein afourth of the five interconnecting members continuously interconnect thefirst member of the second planetary gear set with the first member ofthe third planetary gear set.
 16. The transmission of claim 15 wherein afifth of the five interconnecting members continuously interconnect thesecond member of the third planetary gear set with the second member ofthe fourth planetary gear set.
 17. The transmission of claim 11 whereinthe first members are sun gears, the second members are carrier members,and the third members are ring gears.
 18. The transmission of claim 11wherein one of the torque transmitting devices is a brake and four ofthe torque transmitting devices are clutches.
 19. A transmissioncomprising: an input member; an output member; an intermediate member;first, second, third and fourth planetary gear sets each having a sungear, a carrier member, and a ring gear; a first interconnecting membercontinuously interconnecting the sun gear of the first planetary gearset with a transmission housing; a second interconnecting membercontinuously interconnecting the carrier member of the first planetarygear set with the ring gear of the second planetary gear set; a thirdinterconnecting member continuously interconnecting the ring gear of thefirst planetary gear set with the sun gear of the fourth planetary gearset; a fourth interconnecting member continuously interconnecting thesun gear member of the second planetary gear set with the sun gear ofthe third planetary gear set; a fifth interconnecting membercontinuously interconnecting the carrier member of the third planetarygear set with the carrier member of the fourth planetary gear set; afirst torque transmitting device selectively engageable to interconnectat least one of the carrier member of the second planetary gear set andthe input member with the intermediate member; a second torquetransmitting device selectively engageable to interconnect at least oneof the ring gear of the first planetary gear set and the sun gear of thefourth planetary gear set with the intermediate member; a third torquetransmitting device selectively engageable to interconnect at least oneof the sun gear of the third planetary gear set and the sun gear of thesecond planetary gear set with the intermediate member; a fourth torquetransmitting device selectively engageable to interconnect the ring gearof the fourth planetary gear set with the intermediate member; and afifth torque transmitting device selectively engageable to interconnectthe ring gear of the third planetary gear set with the transmissionhousing, and wherein the torque transmitting devices are selectivelyengageable in combinations of at least three to establish a plurality offorward speed ratios and at least one reverse speed ratio between theinput member and the output member.
 20. The transmission of claim 19wherein the input member is continuously interconnected with the carriermember of the second planetary gear set and wherein the output member iscontinuously interconnected with the carrier member of the thirdplanetary gear set and the carrier member of the fourth planetary gearset.